1. Field of the Invention
The invention relates to a gearbox supporting means of a wind turbine that has a rotor, a substantially horizontally oriented rotor shaft, a gearbox and a main frame, comprising at least one rolling bearing arranged between a rotor hub and the gearbox and at least two supports on the gearbox. The supports each have at least one central supporting body, at least one frame and a plurality of flat elastomer bodies that are or can be clamped between the frame and the supporting body. The invention further relates to a wind turbine and a method for maintaining a gearbox supporting means for a wind turbine.
2. Description of Related Art
Many modern wind turbines with substantially horizontally oriented rotor shaft axes have a gearbox in a nacelle or respectively a power house on the top of the tower, which connects the rotor with a generator. A main frame is housed in the nacelle, on which the generator and the gearbox are mounted. Since the main frame must also carry the rotor, a three-point support or a four-point support is normally used.
The three-point support which is named, as an example, comprises a rolling bearing, through which the rotor shaft is guided and which supports the rotor shaft. Two additional bearing points are arranged laterally on the gearbox and fasten the gearbox on the main frame. These lateral bearings also absorb the gearbox torque and are called supports or respectively gearbox supports.
In most existing wind turbines with gearboxes, the rolling bearing on the rotor shaft is designed as a fixed bearing, which means that this rolling bearing absorbs rotor thrust that is transferred to the rotor by the wind and transfers it to the main frame. The transmission is thereby not loaded with the corresponding rotor thrust and is thus preserved. In this case, the rotor shaft and the rolling bearing are designed in a very stable manner. The supports located laterally on the gearbox are then designed as floating bearings so that they are designed as being soft in the axial direction, i.e. parallel to the rotor shaft axis.
Another function of the bearings, in particular the supports, is the decoupling of structure-borne sound of the gearbox from the main frame. Normally, in known gearbox supports and in order to facilitate structure-borne sound decoupling, each bolt head is encased in a cylindrical rubber layer, also called a “bushing”, which buffers both vertical as well as horizontal loads. Such bearings are soft in the axial direction, i.e. parallel to the rotor shaft axis. The geometry of the bolt is specified by the rubber bushing. An adjustment of the stiffness for the specified geometry is possible through the selection of the elastomer materials. The elastomer bushings also provide structure-borne sound decoupling of the gearbox and are frequently designed as cylinder half-shells. The attachment parts of these elastomer bodies can be produced with traditional machining processes, for example drilling and turning.
In the design of the bearings, the transfer of high loads, amounting namely to a couple of hundred tons, an effective sound decoupling, ease of replacement of the elastomer elements that have aged under stress as well as an economical production of the structure-borne sound decoupling as well as of the connection construction are to be taken into consideration.
A suspension system is known from U.S. Pat. No. 7,819,624 B2, in which several planar elastomer bodies are used on different sides, which are rigid vis-à-vis a compression, instead of a cylindrical elastomer body. They are arranged around a central bearing and are clamped in an outer frame.
The use of elastic flat bodies as supports of a gearbox of a wind turbine is also known from EP 1 197 677 A2, in which the gearbox comprises laterally two bearing bodies having a rhomboid cross-section, on each of which a flat body is arranged obliquely to each other on the top and on the bottom. The four flat bodies left and right of the gearbox together have a rhomboid shape.
The technical teaching in WO 2008/028616 A2 goes a different route, in which a support of a wind turbine uses two conical elastomer bodies with a vertical symmetry axis, with which a permanent support of the gearbox is also realized.
EP 1 867 871 A2 discloses a torque support that can be knocked off, which discloses a fixed bearing with cone elements and a flying arrangement.